Of course, I hope Vick stays healthy, but I'm hearing quite a bit about how much the Eagles' success this year depends on him staying so. I really tend to doubt this will be the case, simply because Vince Young is quite a good player in his own right, as I'll illustrate below:
Last year, Vick played in 12 games, and had a 60% completion %, with a Yard Per Attempt (YPA) of 8.11. He was helped by a ridiculous and likely unrepeatably low INT % of only 6 INTs (1.6%). He contributed with his legs another 676 Yards (56 per game). In advanced metrics, his DVOA passing was ranked 11th, and rushing he was #1 for QBs, and #8 overall.
Last year, Young had a pretty good year too. Starting 8 games, he threw for a 59.6% completion %, and 8.04 YPA. He only threw 3 INTs for a similarly awesome (and unsustainable) INT % of 1.9%. He ran with much less success than Vick (what a shock!) for only 125 yards (16 per game). In advanced metrics, his DVOA passing was ranked 5th, which you will note is higher than Vick, and his running DVOA is below average at 23rd.
This is not an in-depth study, comparing the receivers Young had vs. the Eagles, and it's not intended to speculate what Young might do with Reid, Morty & Co to work with for any length of time. Just comparing the two QBs, it seems to me that though there is a drop off between #1 and #2, it's really not that large. Assuming that Vick gets hurt, the offense as a whole will likely not skip many beats between our probably great running attack and a passer who is similar, and almost as good, as our #1 guy. All in all, I want Vick to be the guy. But I feel quite comfortable should he go down in relying on Vince Young.
PS Apologies for the crappy formatting, I'm having trouble with this website for some reason...